Injector driving apparatus

Abstract

In an injector driving apparatus, a driving circuit supplies a current individually to each coil of multiple injectors, a current detection element detects the current flowing in a common current flow path, which is common to the coils, a current supply period guard part forcibly stops the current supplied from the driving circuit to the coil upon determination that a measured period reached a predetermined set period based on a detection result of the current detection element, and a diagnosis part operates in a period of no fuel injection to check whether the current supply period guard part normally stops the current supplied to the coil, by continuously supplying the current to the coil for only a short period, which disables the injector to open a valve, and sequentially switches over the coils.

What is claimed is: 
     
       1. An injector driving apparatus comprising:
 a driving circuit for supplying a current individually to coils of multiple injectors mounted on an engine of a vehicle; 
 a common current flow path, in which a current flows to the coils in common; 
 a current detection element provided in the common current flow path for detecting the current flowing in the common current flow path as a current, that flows to the coils; 
 a current supply period guard part for measuring a period, during which the current continues to flow in the common current flow path, based on a detection result of the current detection element, and forcibly stopping the current supplied from the driving circuit to the coils when a measured period reaches a predetermined set period; and 
 a diagnosis part for checking whether the current supply period guard part normally stops the current supplied from the driving circuit to the coils,
 by supplying the current to each of the coils for a period shorter than a minimum period, which enables an injector to open a valve, and 
 by sequentially switching over the coils thereby to continuously supply the current to the common current flow path, 
 
 wherein the diagnosis part performs a checking operation in a period of no fuel injection into the engine. 
 
     
     
       2. The injector driving apparatus according to  claim 1 , wherein:
 the diagnosis part determines that the current supply period guard part is abnormal when the current is not stopped from being supplied to the coil even in a case of a continuous current supply to the common current flow path for a period longer than the set period. 
 
     
     
       3. The injector driving apparatus according to  claim 1 , wherein:
 the diagnosis part operates in a period, during which power is supplied to the injector driving apparatus after an ignition switch of the vehicle is turned off. 
 
     
     
       4. The injector driving apparatus according to  claim 1 , wherein:
 the diagnosis part operates in a period from when an ignition switch of the vehicle is turned on to when an engine cranking is started. 
 
     
     
       5. The injector driving apparatus according to  claim 1 , wherein:
 the diagnosis means operates in a period, during which the engine is automatically stopped under an idle-stop control. 
 
     
     
       6. The injector driving apparatus according to  claim 1 , wherein:
 the diagnosis part operates in a period, during which fuel injection to the engine is shut off upon deceleration of the vehicle. 
 
     
     
       7. The injector driving apparatus according to  claim 1 , wherein:
 the current measured by the current supply period guard part is higher than a set current value.